Usability and Feasibility of PmEB: A Mobile Phone Application for Monitoring Real Time Caloric Balance Christopher C. Tsai & Gunny Lee & Fred Raab & Gregory J. Norman & Timothy Sohn & William G. Griswold & Kevin Patrick Published online: 15 July 2007 # Springer Science + Business Media, LLC 2007 Abstract Obesity is a major public health challenge with over 65% of US adults either overweight or obese. Estimated annual costs of obesity are $78.5 billion. Self- monitoring is a critical skill for successful weight manage- ment. However, self-monitoring is labor-intensive, and compliance is often difficult. In this paper, the authors describe the Patient-Centered Assessment and Counseling Mobile Energy Balance (PmEB) mobile phone application that allows users to self-monitor caloric balance in real time. The application was developed and applied in a four- phase iterative research and development methodology. A usability study and a preliminary feasibility study were conducted. The 1 month feasibility study measured com- pliance and satisfaction among a sample of 15 participants randomized to one of three groups: (1) a paper diary group, (2) a PmEB group with one daily prompt, and (3) a PmEB group with three daily prompts. PmEB scored highly on usability, compliance, and satisfaction. In addition, mobile phone group users scored PmEB the same as or better than Paper Group members scored the paper diary in nearly all categories. Thematic analysis of comments revealed very positive reviews of PmEB as well as areas for improve- ment. PmEB is both usable and feasible for weight management self-monitoring, and the iterative pilot study methodology was effective in improving its usability. Keywords behavioral science . mobile communication . software prototyping . user centered design methodology 1 Introduction Approximately 65% of US adults are currently overweight or obese. Obesity increases risk for many chronic diseases such as cardiovascular disease, diabetes, and numerous cancers. Estimated annual costs of obesity in the USA in 1998 were $78.5 billion [1], with half paid by Medicare and Medicaid, and the remainder paid by private sources and out-of-pocket. Diet and physical inactivity are the main modifiable determinants of obesity [2]. From the National Weight Control Registry [3], men and women who have maintained at least a 30 lb weight loss for a minimum of 1 year report monitoring their weight on a daily or weekly basis. Overall, self-monitoring has emerged as a critical skill for obesity management [3, 4]. However, detailed self- Mobile Netw Appl (2007) 12:173–184 DOI 10.1007/s11036-007-0014-4 C. C. Tsai (*) Decision Systems Group, Brigham & Women’ s Hospital, Boston, MA 02115, USA e-mail: ctsai@dsg.harvard.edu G. Lee SCIL Group, Stanford University, Stanford, CA 94305, USA e-mail: gulee@stanford.edu F. Raab : G. J. Norman : K. Patrick Family and Preventive Medicine, University of California, San Diego, CA 92122, USA F. Raab e-mail: fraab@paceproject.org G. J. Norman e-mail: gnorman@paceproject.org K. Patrick e-mail: kpatrick@paceproject.org T. Sohn : W. G. Griswold Computer Science and Engineering, University of California, San Diego, CA 92122, USA T. Sohn e-mail: tsohn@ucsd.edu W. G. Griswold e-mail: wgg@ucsd.edu